The Chinese windlass is a drive assembly that uses a drum arrangement such as double-drum arrangement in order to drastically reduce the motion evident at end of a winch. Windlasses exist in varying forms and are useful predominantly because of their high reduction capacity. The Chinese windlass greatly reduces the driving torque on the drum, as compared to a standard winch. This is particularly useful when driven by hand or by an electric motor, both of which are capable of putting out relatively low torque.
The conical windlass, illustrated in FIG. 1, is a variant of the double drum windlass. The conical windlass includes a rope wrapped around a conical drum a few times before it passes down and around a pulley to meet itself once again, forming a closed loop of rope. When the crank connected to the conical drum is turned, the coils on the drum shift up and down the drum, and change in size. As they grow larger, the free length of rope between the coils and the pulley shrinks or expands in conservation of the total rope length. The maximally contracted state is at the largest section of the conical drum, at which the pulley and its hook will be at their highest point.